1. Field of the Invention
The present invention relates to closures for chambers and, more particularly, to apparatus for causing the door to assume various positions relative to the chamber opening.
2. Description of the Prior Art
There exists a wide variety of chambers adapted for maintaining pressure within the chamber. An example of such a chamber is a sterilizer that operates under pressure during at least a portion of the sterilizing cycle. To enable pressure to build within the chamber of the sterilizer, it is necessary to provide a seal against fluid flow from the chamber between the perimeter of the chamber opening in the door of the sterilizer. Typically, such a seal is effected by disposing a sealing device between the perimeter of the opening and the door. The sealing device is usually disposed on either the perimeter of the opening or the chamber door. Generally, one of two types of sealing devices is used to effect the fluid seal. The first type, a compression seal, requires that compressive force be exerted on the seal by the door and the perimeter of the opening to the chamber. The second type, a noncompressive seal, does not require the exertion of such a compressive force, but requires only that the seal contact the surfaces of both the perimeter of the opening and the door. Moreover, for reasons related to personnel safety, it is desirable to ensure that positive pressure is not established inadvertently within the chamber of a sterilizer.
Conventional closures for such sterilizers generally comprise a cluster of radial arms or bolts one end of each of which is attached to a circular central hub upon which a threaded nut is mounted. The nut travels along a threaded doorpost which is mounted to the door plate. The door is closed tightly against the chamber by rotating a handwheel that is mounted on the threaded nut through several revolutions. An initial rotation of the handwheel causes the central hub to rotate and push the free ends of the radial arms within a frame mounted on the sterilizer shell and secure the door in a position in which the door confronts the sterilizer opening, but in which the door does not seal the sterilizer. Further rotation of the handwheel pushes the door against the perimeter of the chamber opening.
The nut, the threaded doorpost and the associated closing apparatus are bulky and expensive to manufacture; further, since the mechanism must transfer the torque applied to the handwheel to a linear force exerted against the door through the threaded doorpost, the user must rotate the handwheel through a number of revolutions to secure the door against the perimeter of the chamber opening.
Accordingly, there exists a need for apparatus for securing the door of a chamber capable of maintaining pressure within the chamber, such as a sterilizer, against the perimeter of the opening of the chamber that can be operated more quickly than securing apparatus employing a threaded doorpost.